Currently, as in other fields of technology, integrated circuits are increasingly also being used in automobile technology, for example in the form of microprocessors or microcontrollers. Devices for supplying energy are provided in order to operate them. Known devices of this type generally contain an external blocking capacity (i.e. capacitance or capacitor) which is parallel connected between a supply inlet of the integrated circuit and earth (i.e. ground), and a voltage source which is connected parallel to it. The voltage source charges the blocking capacity, and the energy which is supplied to the integrated circuit is extracted from the blocking capacity by means of a discharge current. The intention is to hereby achieve the most realistic replica possible of an ideal voltage source. However, the known energy supply devices lead to an unwanted high level of radiation of electromagnetic energy, in particular when a cycle frequency of the integrated circuit reaches levels which are greater than 10 MHz. Then, when applicable, the EMC automobile industry standards are also no longer met.
PCT/DE2005/000433 published as WO 2006/094469 and US 2008/197820 describes a device of the type described in the above introduction, with the aid of which an integrated circuit can also be supplied with energy when it has a high cycle rate, in particular in the MHz range, wherein at the same time, the EMC automobile industry standards are also met.
On the one hand, no external circuit is required with the additional blocking capacity. Instead, an internal bus capacity which is already present within the integrated circuit is used. On the other hand, instead of the low-ohmic voltage source used with the known devices, an energy supply with the highest possible internal resistance is used.
The combination of both measures causes a frequency decoupling of the charging and discharging of the bus capacity. While the bus capacity continues to be discharged with the high cycle frequency, by contrast, the charging is achieved with a significantly lower frequency. The latter occurs as a result of the low-pass behavior of the combination of the bus capacity and high-ohmic internal resistance of the supply unit. Regarding the charging, the charging frequencies which occur are at least one order of magnitude smaller than the discharging frequencies which occur in connection with the discharging, which are mainly determined by the fundamental wave (=cycle frequency) of the cycle rate of the integrated circuit and its harmonic waves. Incidental interruptions are created by the internal communication, the fundamental frequency of which is usually operated at half the cycle rate. Signal components with the high-frequency discharging currents are narrowly restricted spatially and are essentially only present within the integrated circuit. Signal components with the low-frequency charging currents also run through a printed circuit board, however, onto which the integrated circuit is mounted. Neither of the signal components creates any significant radiation of electromagnetic energy—the discharge signal component due to the narrow spatial restriction within the integrated circuit, and the charge signal component due to the low frequency.